Slingatron Update

As previously mentioned, the CC3200 got its JTAG connection damaged because I got excited and plugged in the battery before isolating the usb power. Now I’m working with the TM4C123GXL launchpad from TI.

Why the TM4C123GXL? Mostly because it has a similar core to the CC3200, I had one and I had yet to ever do anything with it. It doesn’t have wi-fi or an accelerometer on it, but I can add those later if I want. Feature creep is already a problem.

When my initial design was going, it didn’t want to move much. I think I got lucky when it did work. A more powerful motor would probably do the trick, but I saw a way of getting the platform to oscillate that I’m going to explore instead. Here’s the idea:

Why not just copy someone else’s plans? It’s not like I came up with the idea of a “Slingatron” to start with. Basically, I don’t want to, it’s not as fun. This is an exercise for myself. I’m sure that this is not original by any means but I will create it. I looked through my mechanical movement visual reference book (thanks for buying me that Caroline, it’s very cool) but didn’t see what I wanted right away. It could be in there, there’s a lot of terminology that I don’t know and a lot of examples. Instead, I saw the holes on the robot chassis I’m using as a surface and the above design clicked in my head.

I was busy the rest of the night [after work] hacking it together and it seems like it’s going to give the motion I’m looking for. I’m sure I’ll iterate through the design a few more times. May even design and print some more parts. I am trying to balance this with the actual code. It’s the little bits that get ya. I can make the thing move, but wouldn’t it be nice if I had some control? Where do I draw the line between making it spin and making it user friendly? I guess that’s why projects have goals and milestones. I should have started with that. Never too late, he I go:

“Spinatron” type BB launcher project Project Goals:

The code will be “bare-metal” [no OS] and be interrupt driven.

It will be written in C and developed using IAR Embedded Workbench for ARM 7.40.3.

It will make use of existing API for the embedded peripheral functions.

Using those should keep the code size down because those functions don’t reside in the accessible FLASH. Not that I expect to use much code space in the first place (famous last words?). It should also be more portable to other, similar, TI devices.

I will tryto be consistent with naming conventions and use known best practices while maintaining my style.

While this is a personal project, there’s no reason to not design the code in such a way that it is not a chore to understand or reuse. That being said, I shouldn’t have to be so strict with convention that it’s not fun.

I am responsible for the project.

That doesn’t mean I won’t use open examples to build upon, it means that if the code, hardware or something else fails, it is my fault. That’s what I believe it means to be an Engineer of any sort. The buck stops here.

There will be a start button, stop button, and analog speed control.

“Good Enough” is okay for this project.

“Good Enough” means I’m not going to worry too much about precision and vibrations. The goal is to make it work, not to be anything more than a proof of concept. So I’ll try and get the build done in an evening once I get to that part.

Have fun.

I worry a lot. About everything. Well, except for very special circumstances; that’s how I know it’s a special circumstance. I originally started this project because I saw a picture of a “Slingatron” and knew right away how to design the spiral for my 3D printer. That was fun. I decided to move beyond the 3D print to making it actually function; in hopes of impressing some folks I want to impress. That was a mistake. Things got rushed and I didn’t have much to show myself with. I don’t know if I’ll ever hear back from those folks, but now, I want to make this for me. That means don’t rush, be confident and have fun pulling my hair if it comes to that. I Make best when I make me into it, so do that.

Something I’ve learned by doing:

the spiral tube I printed has split back into its original halves. As it turns out, nylon and super-glue are not the best of friends. Nylon is pretty cool stuff, being able to print things out of it is pretty awesome as well. To paraphrase a friend, “it’s one of the earliest plastics and yet they got so much right with it”